Hepatic bile salt sulphotransferase (BSS) activity and the contents of unconjugated oestradiol-17 beta (E2) and conjugated oestrone (cE1) in liver tissue was significantly lower in young essential fatty acid (EFA) deficient female rats than in female control rats. No corresponding differences were found between male EFA deficient and control rats. A significant sex difference, with higher values in females, was found for BSS activity and E2 and cE1 contents in control rats but not in EFA deficient rats. The decrease in hepatic BSS activity in female rats caused by EFA deficiency may be mediated via a decreased estrogenic action on the liver.